The enamel layer of the tooth is naturally an opaque white or slightly off-white colour. However, this enamel layer can become stained or discoloured. The enamel layer of the tooth is composed of hydroxyapatite mineral crystals that create a somewhat porous surface. It is believed that this porous nature of the enamel layer allows staining agents and discolouring substances to permeate the enamel and discolour the tooth.
Many products we consume have a negative impact on our teeth and mouth. Many substances can stain or reduce the whiteness of one's teeth, in particular, certain foods, tobacco products, and fluids such as tea and coffee. These staining and discolouring substances are often able to permeate the enamel layer. This problem occurs gradually over many years, but imparts a noticeable discoloration of the enamel of one's teeth.
Consumers have always had a strong desire for white teeth and many individuals are dissatisfied with their current teeth colour. This desire for whiter teeth has given rise to a growing trend in the increased use of tooth whitening products.
A variety of products are currently used for teeth whitening. Such products often comprise peroxides, abrasives or both in order to clean and whiten teeth. These types of products are often not desired since they do not contribute to the remineralization of teeth and can cause damage to teeth and gums if overused. Products comprising calcium source have been developed in an attempt to enhance the characteristics of teeth. Such products, however, do not positively adhere to teeth and thereby may only contact teeth for a brief period of time prior to being rinsed out of the mouth in wash water.
The present inventors have now recognized a need to develop an oral care product which has tooth whitening agents that are suitable to adhere to the surface of teeth for a long enough period of time to provide not only instant but also long-lasting whitening benefits to teeth. It has been found that calcium silicate, especially calcium silicate in the form of a hydrate can behave as a deposition aid and unexpectedly enhances the deposition of particulate tooth whitening agent on tooth surfaces which delivers both instant and excellent long-lasting tooth whitening benefits.
Additional Information
WO 2008/068149 A (Unilever) discloses an oral care product comprising a first composition comprising an insoluble calcium salt that is not a calcium phosphate salt, a second independent composition comprising a source of phosphate ions, and a means for delivering each of the compositions to the surface of the teeth. The preferred insoluble calcium salt is calcium silicate.
WO 2008/015117 A (Unilever) discloses a calcium oxide-silica composite biomaterial either in amorphous state or crystalline state having an average pore size, as determined by the BET method, in the range of from 0.8 to 4 nm, wherein the calcium oxide-silica content of the biomaterial is at least 80 wt percent, the balance being optionally one or more other materials and wherein the molar ratio of calcium oxide to silica is at least 0.1.
WO 2012/031785 A (Unilever) discloses composite particle actives suitable for use in oral care compositions. The composite particle actives have a core and a coating whereby the coating interacts with phosphate ions to produce calcium and phosphate reaction products that are suitable to adhere to tooth enamel and/or dentin in order to improve characteristics of teeth.
WO 2012/031786 A (Unilever) discloses oral care compositions with composite particle actives described in WO 2012/031785 A (Unilever).
None of the additional information above describes an oral care composition comprising calcium silicate, particularly calcium silicate hydrate as a deposition aid which enhances the deposition of particulate whitening agents on teeth surface in order to achieve excellent instant and long-lasting tooth whitening results.